My boinc client is working for mor than 40 hours but there are still no credits.

???
1. As far as I can see you have no host attached to BURP, so I don't think you are crunching a work unit from here...
2. You don't get credits during crunching, you get credits when a work unit is finished/done, uploaded and validated
____________Life is Science, and Science rules. To the universe and beyond
Proud member of BOINC@HeidelbergMy BOINC-Stats

From different projects? No, of course not.
I guess you are referring to statistics, and for that are stats sites like BOINCstats, Free-DC etc.
____________Life is Science, and Science rules. To the universe and beyond
Proud member of BOINC@HeidelbergMy BOINC-Stats

You need to attach your host via the BOINC manager to this url: http://burp.renderfarming.net/
Then your pc will getting work units from BURP.
If you haven't readed it yet, I recommend the page "Getting started", the most you need to know for the basics are there.
____________Life is Science, and Science rules. To the universe and beyond
Proud member of BOINC@HeidelbergMy BOINC-Stats

How can I earn points (credits) here to make possible to render something when it's neccesary?

Currently, it doesn't cost anything to have your work rendered. However, it's preferred to have you helping out with the renders of other people as well, since that's both the polite thing to do and will ensure you have a lot of credits banked up if/when it becomes necessary.
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